A groundbreaking satellite set to launch on Tuesday will have the ability to see through clouds and dense foliage to evaluate how forests help protect the planet from climate change. The Biomass satellite, developed by the European Space Agency, will "weigh" the Earth's forests, revealing the amount of carbon stored in trees and, consequently, the carbon that is kept out of the atmosphere.
Until now, calculating the carbon stored by the 1.5 trillion trees in the world's rainforests has been nearly impossible. Led by the British company Airbus, this project aims to help scientists model climate change more accurately and monitor deforestation rates.
The satellite will launch at 10:15 BST from the European Space Agency's Kourou spaceport in French Guiana. It has been affectionately dubbed the "space brolly" due to its large 12-meter diameter antenna that expands outward. This antenna will utilize radar with a very long wavelength, allowing it to penetrate deeper into forests and reveal branches and trunks that are hidden by the canopy.
"Most radars currently in space provide excellent images of icebergs, but when they observe forests, they only capture the tops—the small twigs and leaves—without penetrating deeper," explained Dr. Ralph Cordey, head of geosciences at Airbus. "However, by using a much longer radar wavelength, we've found that we can see into the depths of trees and forests," he added.
Weighing 1.2 tons, the satellite will use a technique similar to that of a CT scan, analyzing cross-sections of trees during repeated passes to build a comprehensive picture of the woody material present. This material serves as a proxy for the amount of planet-warming carbon dioxide stored in the forest.
Currently, scientists measure individual trees and extrapolate data, but this method presents significant challenges, according to Professor Mat Disney, a remote sensing expert at University College London. "Our current understanding is patchy because it is incredibly difficult to measure," he stated. "Essentially, we're trying to weigh the carbon stored in 1.5 trillion trees across the tropics. Satellites are the only consistent way to achieve this."
Ground measurements will continue after the satellite launches to verify the data it transmits back.
Despite years of testing, the launch itself is expected to pose some challenges. "Some components on the satellite are quite large, including its 12-meter deployable antenna. It's similar to deploying a very large umbrella in space, so we'll be watching closely to ensure that it unfolds smoothly," said Dr. Cordey. Airbus enlisted engineers from the American company L3Harris Technologies to oversee the construction of the antenna-reflector. L3Harris specializes in large, unfurlable systems—expertise that is currently lacking in Europe.
If the launch goes as planned, the team aims to produce the first maps within six months and will continue to collect data for the next five years. These annual maps will not only indicate how much carbon is stored but also how much is lost due to deforestation.
"The observations we've had for the last 50 years from other satellites, like Landsat, have been heavily impacted by clouds. In tropical regions, cloud cover is frequent, so important sections of tropical forest may go unseen," said Professor Disney. Another advantage of the Biomass satellite's longer wavelength is its ability to penetrate clouds, providing a consistent and comparable view of forests year after year.
This is the outcome that has motivated the scientists involved in the project for over 20 years. "It's exciting because it will inform us about the role of something we might take for granted—our forests and trees—in the processes governing our planet, particularly those related to climate change that are crucial for today and the future," said Dr. Cordey.